Humidifiers are employed routinely in buildings, homes and the like to add moisture to the surrounding air, particularly during the winter months. The water vapor is generated by methods such as heating water in passage through a heater coil and by vibrating transducer coils to cavitate water into a vapor. Unfortunately, mineral deposits within the supplied water, and bacteria in both the water and surrounding air accumulate within the humidifier. As a result, the operational efficiency of the humidifier is impaired, and more importantly, bacteria emitted in the water vapor can pose a significant health threat to people breathing the humidified air.
De-ionized water has been successfully used to inhibit the accumulation of mineral deposits in humidifiers. However, no single solution is currently favored to retard bacteria accumulation within humidifiers. One approach is disclosed in U.S. Pat. No. 3,952,181 wherein a heating coil is dedicated to raising the supply water temperature sufficiently high to kill bacteria before the water is vaporized by a separate water receiving/steam generating coil. One drawback with this solution is that energizing the additional coil adds significantly to the power consumption and operating costs of the humidifier. Furthermore, such a solution is inapplicable to ultrasonic humidifiers which produce water vapor through a non-heating approach.
Another approach is disclosed in U.S. Pat. No. 4,663,091 wherein positive and negative electrical terminals are separated from one another in porously-separated internal cavities. The application of electric current to the terminals results in the sterilization of the water within the humidifier. Unfortunately, the humidifier requires additional parts and valves within its housing which increases the chances of humidifier malfunction. During malfunction, the humidifier must of course be taken off-line either to be repaired or replaced. In addition, the current necessary to maintain electrolysis of the water adds significantly to the operating costs of the humidifier.
It is an object of the present invention to overcome the drawbacks and disadvantages of prior apparatus and methods for inhibiting the accumulation of bacteria within a humidifier.